<?php
// Consider that the 0 could by any parameters including itself
var_dump(0 == 1); // false
var_dump(0 == (bool)'all'); // false
var_dump(0 == 'all'); // TRUE, take care\
var_dump(1 == '1all');
var_dump(0 === 'all'); // false

// To avoid this behavior, you need to cast your parameter as string like that :
var_dump((string)0 == 'all'); // false
//原理：数字和字符串进行比较时，当这个字符串是一个无法转换为数字的字符串，它就会被强制转化为数字，结果总是为0 
